Image forming processes are available in which, in order that electric or magnetic latent images on a recording member are made into visible images, the latent images are rendered visible by the used of a toner. As what is typical among these, it may include an electrophotographic process. In this electrophotographic process, first a latent image is electrically formed on a photosensitive member by various means, and subsequently the latent image is developed by the use of a toner to form a toner image. Thereafter, the toner image is transferring to a transfer material such as paper as occasion calls, and then the toner image is fixed to the transfer material by a fixing means such as heat, pressure, heat-and-pressure or solvent vapor, thus an image is obtained.
A heat roller fixing method or a film fixing method is a method in which toner images held on a fixing medium sheet (a sheet to which toner images are to be fixed) is fixed thereto by making them pass a heat roller or a fixing film in contact therewith. In this fixing method, the surface of the heat roller or fixing film and the toner on the fixing medium sheet come into contact with each other, and hence a very good heat efficiency is achievable when the toner is fused onto the fixing medium sheet. This enables performance of rapid fixing, and is very good for electrophotographic apparatus. In this fixing method, F however, since the toner comes into contact with the surface of the heat roller or fixing film in a molten state, part of the toner adheres to the surface of the heat roller or fixing film. Hence, an offset phenomenon in which the toner having adhered to the surface of the heat roller or fixing film is again transferred to a next fixing medium sheet may occur to contaminate the fixing medium sheet.
Taking account of recent demands for making apparatus compact, light-weight, energy-savable and highly reliable, such demands can not completely be met unless the performance of toners such as fixing performance and anti-offset properties is further improved. Such improvement is difficult to achieve unless the toners are further improved.
Japanese Patent Application Laid-open No. 2002-6553 discloses a toner which contains a low-molecular weight resin having a peak or a shoulder in a specific molecular weight region and a high-molecular weight resin having a peak or a shoulder in a specific molecular weight region, and also has a polyolefin type wax.
Japanese Patent No. 2630972 also discloses a toner in which the molecular weight distribution of THF-soluble matter as measured by GPC and the glass transition points of a binder resin and a toner have been prescribed.
Japanese Patent Application Laid-open No. H10-333359 still also disclose a toner which has prescribed specific molecular weight distribution and weight-average molecular weight.
However, it is desired to provide a toner having achieved more low-temperature fixing performance and higher glossiness than the toners disclosed in the above patent publications.